Try deleting ~/.bitcoin (make sure you backup your wallet in ~/.bitcoin/wallet.dat if you've used it!) and then reopen bitcoin-qt. I had that message when the blockchain download got interrupted on an old install.
unable rmdir ~/.bitcoin but rm * and rmdir all inside and now works ! THANKS
You could have done 'rm -r ~/.bitcoin' I don't think I've ever even used 'rmdir'
What version does the ppa install? .6 has some speed improvements for the initial blockchain download.
version installed 0.6, works much faster that MSWindows version, i don't know why...
now i need to know how to copy my wallet to the directory...
You are very new to linux, aren't you?